What is the role of small intestinal bacterial overgrowth (SIBO) in IBS?
SIBO is a condition in which excessive levels of bacteria, predominantly the colonic-type species, are present in the small intestine. SIBO appears to be more common in IBS, although the reported incidence of SIBO varies according to the detection method employed. A recent systematic review and metaanalysis found the rate of a positive breath test (lactulose and glucose) to be 54% (95% confidence interval [CI], 32%-76%) and 31% (95% CI, 14%-50%), respectively. The prevalence of a positive jejunal aspirate and culture was 4% to 12%. The odds ratio for any positive test for SIBO in IBS was 3.5 to 4.7, depending on the criteria used to define a positive test.